10kV Bus Voltage Switching

10kV bus voltage switching involves automatic sectionalized switching, fault recovery strategies, and the use of SiC-based power devices for efficient and reliable medium-voltage operation.

Automatic Sectionalized Switching

In a single-bus three-section annular 10kV bus, automatic sectionalized spare power switching is used to maintain continuity of supply during faults or transformer outages. The process involves identifying the voltage-loss bus and the main supply low-voltage switch, then executing a priority-based switching action through sectional switches after a delay to prevent overloading the main transformer. If the switching fails, the system returns to its initial state to ensure safety and prevent loop closure issues .

Fault Recovery and Load Transfer

When a 10kV bus fault causes a large-area outage, distribution network restoration requires a switching operation sequence to safely transfer load to alternate feeders. This involves:

• Modeling the network using a simplified graph-based representation of nodes (switches and breakers) and edges (feeders and transformers)
• Establishing a constraint satisfaction problem to minimize load shedding and economic loss
• Generating load modes for interconnection elements and determining the optimal switching sequence for rapid restoration This approach ensures that power is restored efficiently while avoiding closed-loop conditions that could damage equipment.

SiC-Based Medium-Voltage Switching

Modern 10kV SiC MOSFETs enable high-speed, high-efficiency switching for medium-voltage applications. Key advantages include:

• High blocking voltage and fast switching speeds, reducing losses and improving reliability
• Improved thermal performance, allowing higher overload capability
• Simplified converter topologies, reducing the number of devices and switching losses
• Series-connected SiC devices can handle 10kV DC bus voltages with balanced voltage sharing and RC snubbers to manage switching transients These devices are particularly useful in solid-state transformers (SSTs) and medium-voltage DC-DC converters, enabling safer and more compact 10kV bus switching solutions.

Practical Considerations

• Delay timing and priority strategies are critical in automatic switching to prevent transformer overloads
• Network modeling and switching sequences are essential for large-area fault recovery
• SiC MOSFET modules require careful thermal and parasitic inductance management to ensure safe operation at 10kV By combining automatic sectionalized switching, optimized restoration sequences, and SiC-based power electronics, 10kV bus voltage switching can achieve high reliability, fast fault recovery, and improved efficiency in modern distribution networks.